1. Field of the Invention
The present invention relates to a particle analyzing system for a clean room smock and a method of analyzing particles. More particularly, the present invention accurately measures the amount of the particles emanating from the clean room smock that is used in the semiconductor device fabrication process.
2. Description of the Related Art
Semiconductor device fabrication processes are generally performed within a highly-purified clean room because even very fine particles can contaminate the devices, thereby causing device malfunctions or inferior quality devices.
In order to reduce particle contamination generated by the manufacturing personnel, clean room operators and technicians wear a clean room smock covering their entire body, including headgear, mask, gloves, shoes, etc. The seams of the clean room smock are also specially manufactured to prevent particle generation as much as possible, and the seams are located on the back side of the smock. In addition, the clean room smock itself is made of a material which produces the least amount of particles as possible.
Despite such precautions, particles produced by the operators and the clean room smock itself still enter the clean room, and such contamination constitutes the main cause of device failure or malfunctions.
Efforts continue to try and improve the clean room smock itself, as well as employing test apparatus to measure and analyze the causes of particle generation. Such conventional test apparatus include a body box tester, a garment chamber, a Tumbler tester, and a Helmkedram tester.
In the body box tester, an operator wearing the clean room smock performs various fabrication processes inside a hexahedral box-shaped chamber for a certain time while the air stream within the chamber flows downward. The particles produced by the operator are collected, and the number of the particles having a size greater than a certain level is determined.
The garment chamber test is similar to the body box tester, with the added benefit that particles generated within the upper part of the chamber can be analyzed separately from those generated in the lower part of the chamber.
In the Tumbler tester and Helmkedram tester, a clean room smock is placed in a chamber and rotated for a certain period to pressurize or inflate the clean room smock. The particles generated by the clean room smock due to the pressurization are collected, and the number of the particles having a size greater than a certain level is determined.
Particle counters employing lasers are installed in each of the body box tester, the garment chamber, the Tumbler tester, and the Helmkedram tester so as to measure the number of the particles having a size greater than a certain level.
However, the particle measurement results from the body box tester and the garment chamber are usually different, with the measurements being dependent on, among other things, the personal cleanliness of the operator, the smoothness of the operator's movements inside the chamber, the kind of the clothes worn by the operator under the clean room smock, and the measurement time.
In addition, more particles are produced from certain parts of the operator's body such as the face, i.e. nose and mouth, compared with other parts of the body, but the body box tester and the garment chamber only measure an aggregate of particles collected, and cannot measure the number of particles produced from discrete parts of the body.
Further, the Tumbler tester and the Helmkedram tester only measure the number of the particles produced by the clean room smock itself, without consideration of the particles produced by an operator, so that the reliability of the measurement results is low and the measurement result varies according to the initial cleanliness of the clean room smock.